CREBBP and STAT6 co-mutation and 16p13 and 1p36 loss define the t(14;18)-negative diffuse variant of follicular lymphoma.
ABSTRACT: The diffuse variant of follicular lymphoma (dFL) is a rare variant of FL lacking t(14;18) that was first described in 2009. In this study, we use a comprehensive approach to define unifying pathologic and genetic features through gold-standard pathologic review, FISH, SNP-microarray, and next-generation sequencing of 16 cases of dFL. We found unique morphologic features, including interstitial sclerosis, microfollicle formation, and rounded nuclear cytology, confirmed absence of t(14;18) and recurrent deletion of 1p36, and showed a novel association with deletion/CN-LOH of 16p13 (inclusive of CREBBP, CIITA, and SOCS1). Mutational profiling demonstrated near-uniform mutations in CREBBP and STAT6, with clonal dominance of CREBBP, among other mutations typical of germinal-center B-cell lymphomas. Frequent CREBBP and CIITA codeletion/mutation suggested a mechanism for immune evasion, while subclonal STAT6 activating mutations with concurrent SOCS1 loss suggested a mechanism of BCL-xL/BCL2L1 upregulation in the absence of BCL2 rearrangements. A review of the literature showed significant enrichment for 16p13 and 1p36 loss/CN-LOH, STAT6 mutation, and CREBBP and STAT6 comutation in dFL, as compared with conventional FL. With this comprehensive approach, our study demonstrates confirmatory and novel genetic associations that can aid in the diagnosis and subclassification of this rare type of lymphoma.
Project description:Fifty-five cases of t(14;18)- follicular lymphoma (FL) were genetically characterized by targeted sequencing and copy number (CN) arrays. t(14;18)- FL predominated in women (M/F 1:2); patients often presented during early clinical stages (71%), and had excellent prognoses. Overall, t(14;18)- FL displayed CN alterations (CNAs) and gene mutations carried by conventional t(14;18)+ FL (cFL), but with different frequencies. The most frequently mutated gene was STAT6 (57%) followed by CREBBP (49%), TNFRSF14 (39%), and KMT2D (27%). t(14;18)- FL showed significantly more STAT6 mutations and lacked MYD88, NOTCH2, MEF2B, and MAP2K1 mutations compared with cFL, nodal marginal zone lymphoma (NMZL), and pediatric-type FL (PTFL). We identified 2 molecular clusters. Cluster A was characterized by TNFRSF14 mutations/1p36 alterations (96%) and frequent mutations in epigenetic regulators, with recurrent loss of 6q21-24 sharing many features with cFL. Cluster B showed few genetic alterations; however, a subgroup with STAT6 mutations concurrent with CREBBP mutations/16p alterations without TNFRSF14 and EZH2 mutations was noted (65%). These 2 molecular clusters did not distinguish cases by inguinal localization, growth pattern, or presence of STAT6 mutations. BCL6 rearrangements were demonstrated in 10 of 45 (22%) cases and did not cluster together. Cases with predominantly inguinal presentation (20 of 50; 40%) had a higher frequency of diffuse growth pattern, STAT6 mutations, CD23 expression, and a lower number of CNAs, in comparison with noninguinal cases (5.1 vs 9.1 alterations per case; P < .05). STAT6 mutations showed a positive correlation with CD23 expression (P < .001). In summary, t(14;18)- FL is genetically a heterogeneous disorder with features that differ from cFL, NMZL, and PTFL.
Project description:Fluorescence in situ hybridization was performed to characterize 81 cases of myeloid and lymphoid malignancies with cytogenetic 1p36 alterations not affecting the PRDM16 locus. In total, three subgroups were identified: balanced translocations (N?=?27) and telomeric rearrangements (N?=?15), both mainly observed in myeloid disorders; and unbalanced non-telomeric rearrangements (N?=?39), mainly observed in lymphoid proliferations and frequently associated with a highly complex karyotype. The 1p36 rearrangement was isolated in 12 cases, mainly myeloid disorders. The breakpoints on 1p36 were more widely distributed than previously reported, but with identifiable rare breakpoint cluster regions, such as the TP73 locus. We also found novel partner loci on 1p36 for the known multi-partner genes HMGA2 and RUNX1. We precised the common terminal 1p36 deletion, which has been suggested to have an adverse prognosis, in B-cell lymphomas [follicular lymphomas and diffuse large B-cell lymphomas with t(14;18)(q32;q21) as well as follicular lymphomas without t(14;18)]. Intrachromosomal telomeric repetitive sequences were detected in at least half the cases of telomeric rearrangements. It is unclear how the latter rearrangements occurred and whether they represent oncogenic events or result from chromosomal instability during oncogenesis.
Project description:For multiple sclerosis, genome wide association studies and follow up studies have identified susceptibility single nucleotide polymorphisms located in or near CLEC16A at chromosome 16p13.13, encompassing among others CIITA, DEXI and SOCS1 in addition to CLEC16A. These genetic variants are located in intronic or intergenic regions and display strong linkage disequilibrium with each other, complicating the understanding of their functional contribution and the identification of the direct causal variant(s). Previous studies have shown that multiple sclerosis-associated risk variants in CLEC16A act as expression quantitative trait loci for CLEC16A itself in human pancreatic ?-cells, for DEXI and SOCS1 in thymic tissue samples, and for DEXI in monocytes and lymphoblastoid cell lines. Since T cells are major players in multiple sclerosis pathogenesis, we have performed expression analyses of the CIITA-DEXI-CLEC16A-SOCS1 gene cluster in CD4+ and CD8+ T cells isolated from multiple sclerosis patients and healthy controls. We observed a higher expression of SOCS1 and CLEC16A in CD4+ T cells in samples homozygous for the risk allele of CLEC16A rs12927355. Pair-wise linear regression analysis revealed high correlation in gene expression in peripheral T cells of CIITA, DEXI, CLEC16A and SOCS1. Our data imply a possible regulatory role for the multiple sclerosis-associated rs12927355 in CLEC16A.
Project description:An acute myeloid leukemia was suspected of having a t(8;16)(p11;p13) resulting in a KAT6A-CREBBP fusion because the bone marrow was packed with monoblasts showing marked erythrophagocytosis. The diagnostic karyotype was 46,XY,add(1)(p13),t(8;21)(p11;q22),der(16)t(1;16)(p13;p13)/46,XY; thus, no direct confirmation of the suspicion could be given although both 8p11 and 16p13 seemed to be rearranged. The leukemic cells were examined in two ways to find out whether a cryptic KAT6A-CREBBP was present. The first was the "conventional" approach: G-banding was followed by fluorescence in situ hybridization (FISH) and reverse transcription PCR (RT-PCR). The second was RNA-Seq followed by data analysis using FusionMap and FusionFinder programs with special emphasis on candidates located in the 1p13, 8p11, 16p13, and 21q22 breakpoints. FISH analysis indicated the presence of a KAT6A/CREBBP chimera. RT-PCR followed by Sanger sequencing of the amplified product showed that a chimeric KAT6A-CREBBP transcript was present in the patients bone marrow. Surprisingly, however, KATA6A-CREBBP was not among the 874 and 35 fusion transcripts identified by the FusionMap and FusionFinder programs, respectively, although 11 sequences of the raw RNA-sequencing data were KATA6A-CREBBP fragments. This illustrates that although many fusion transcripts can be found by RNA-Seq combined with FusionMap and FusionFinder, the pathogenetically essential fusion is not always picked up by the bioinformatic algorithms behind these programs. The present study not only illustrates potential pitfalls of current data analysis programs of whole transcriptome sequences which make them less useful as stand-alone techniques, but also that leukemia diagnosis still relies on integration of clinical, hematologic, and genetic disease features of which the former two by no means have become superfluous.
Project description:Acquired aplastic anemia (aAA) results from the T cell-mediated autoimmune destruction of hematopoietic stem cells. Factors predicting response to immune suppression therapy (IST) or development of myelodysplastic syndrome (MDS) are beginning to be elucidated. Our recent data suggest most patients with aAA treated with IST develop clonal somatic genetic alterations in hematopoietic cells. One frequent acquired abnormality is copy-number neutral loss of heterozygosity on chromosome 6p (6p CN-LOH) involving the human leukocyte antigen (HLA) locus. We hypothesized that because 6p CN-LOH clones may arise from selective pressure to escape immune surveillance through deletion of HLA alleles, the development of 6p CN-LOH may affect response to IST. We used single nucleotide polymorphism array genotyping and targeted next-generation sequencing of HLA alleles to assess frequency of 6p CN-LOH, identity of HLA alleles lost through 6p CN-LOH, and impact of 6p CN-LOH on response to IST. 6p CN-LOH clones were present in 11.3% of patients, remained stable over time, and were not associated with development of MDS-defining cytogenetic abnormalities. Notably, no patient with 6p CN-LOH treated with IST achieved a complete response. In summary, clonal 6p CN-LOH in aAA defines a unique subgroup of patients that may provide insights into hematopoietic clonal evolution.
Project description:Loss of heterozygosity (LOH) at 1p36 is a frequent chromosomal event in a broad range of human cancers with increased incidence observed in nervous system malignancies, including neuroblastoma (NBL). MYCN amplification and 1p36 deletions are highly correlated markers of tumor aggressiveness in NBL. While short distal 1p36 losses are associated with single copy MYCN tumors, larger hemizygous 1p deletions correlate with MYCN amplification, suggesting that two tumor suppressor regions exist in 1p36, a distal and proximal region, which have MYCN-independent and dependent roles. To interrogate this, we genome-edited a proximal candidate, Arid1a, a distal candidate, Chd5, and engineered a syntenic 1p36 LOH deletion in primary mouse NCCs, the likely cell of origin for NBL. Chd5 deletions were found to confer most of the pro-tumorigenic functions of 1p36 LOH in cells expressing endogenous Mycn levels. In contrast, reduced tumor latency in Mycn-driven oncogenesis significantly correlated with the loss of Arid1a. Gene expression analysis found that tumors presenting early onset display a Polycomb Repressive Complex 2 (PRC2) signature and an impaired Trp53 signaling pathway signature. Our findings delineate the tumor suppressor functions of 1p36 LOH in NBL and potentially provide critical insights for the constellation of cancers with 1p36 deletion. Overall design: comparing normal RNA and RNA from NBL tumor models in mice
Project description:Mesangial proliferative glomerulonephritis (MsGN) is a significant global threat to public health. Inflammation plays a crucial role in MsGN; however, the underlying mechanism remains unknown. Herein, we demonstrate that suppression of the cytokine signaling-1 (SOCS1)/signal transducer and activator of transcription 1 (STAT1) signaling pathway is associated with renal inflammation and renal injury in MsGN. Using MsGN rat (Thy1.1 GN) and mouse (Habu GN) models, renal SOCS1/STAT1 was determined to be associated with CD4+ T cell infiltration and related cytokines. In vitro, SOCS1 overexpression repressed IFN-?-induced MHC class II and cytokine levels and STAT1 phosphorylation in mesangial cells. SOCS1 and STAT1 inhibitors significantly inhibited IFN-?-induced CIITA promoter activity and MHC class II expression. In conclusion, our study emphasizes the pivotal role of the SOCS1/STAT1 axis in the regulation of inflammation in MsGN.
Project description:Loss of heterozygosity (LOH) at 1p36 is a frequent chromosomal event in a broad range of human cancers with increased incidence observed in nervous system malignancies, including neuroblastoma (NBL). MYCN amplification and 1p36 deletions are highly correlated markers of tumor aggressiveness in NBL. While short distal 1p36 losses are associated with single copy MYCN tumors, larger hemizygous 1p deletions correlate with MYCN amplification, suggesting that two tumor suppressor regions exist in 1p36, a distal and proximal region, which have MYCN-independent and dependent roles. To interrogate this, we genome-edited a proximal candidate, Arid1a, a distal candidate, Chd5, and engineered a syntenic 1p36 LOH deletion in primary mouse NCCs, the likely cell of origin for NBL. Chd5 deletions were found to confer most of the pro-tumorigenic functions of 1p36 LOH in cells expressing endogenous Mycn levels. In contrast, reduced tumor latency in Mycn-driven oncogenesis significantly correlated with the loss of Arid1a. Gene expression analysis found that tumors presenting early onset display a Polycomb Repressive Complex 2 (PRC2) signature and an impaired Trp53 signaling pathway signature. Our findings delineate the tumor suppressor functions of 1p36 LOH in NBL and potentially provide critical insights for the constellation of cancers with 1p36 deletion. Overall design: Profiling the copy number changes in parental cell lines and tumor samples of neuroblastoma model
Project description:Psoriasis (PS) and Crohn disease (CD) have been shown to be epidemiologically, pathologically, and therapeutically connected, but little is known about their shared genetic causes. We performed meta-analyses of five published genome-wide association studies on PS (2,529 cases and 4,955 controls) and CD (2,142 cases and 5,505 controls), followed up 20 loci that showed strongest evidence for shared disease association and, furthermore, tested cross-disease associations for previously reported PS and CD risk alleles in additional 6,115 PS cases, 4,073 CD cases, and 10,100 controls. We identified seven susceptibility loci outside the human leukocyte antigen region (9p24 near JAK2, 10q22 at ZMIZ1, 11q13 near PRDX5, 16p13 near SOCS1, 17q21 at STAT3, 19p13 near FUT2, and 22q11 at YDJC) shared between PS and CD with genome-wide significance (p < 5 × 10(-8)) and confirmed four already established PS and CD risk loci (IL23R, IL12B, REL, and TYK2). Three of the shared loci are also genome-wide significantly associated with PS alone (10q22 at ZMIZ1, p(rs1250544) = 3.53 × 10(-8), 11q13 near PRDX5, p(rs694739) = 3.71 × 10(-09), 22q11 at YDJC, p(rs181359) = 8.02 × 10(-10)). In addition, we identified one susceptibility locus for CD (16p13 near SOCS1, p(rs4780355) = 4.99 × 10(-8)). Refinement of association signals identified shared genome-wide significant associations for exonic SNPs at 10q22 (ZMIZ1) and in silico expression quantitative trait locus analyses revealed that the associations at ZMIZ1 and near SOCS1 have a potential functional effect on gene expression. Our results show the usefulness of joint analyses of clinically distinct immune-mediated diseases and enlarge the map of shared genetic risk loci.
Project description:Copy number variations (CNV) include net gains or losses of part or whole chromosomal regions. They differ from copy neutral loss of heterozygosity (cn-LOH) events which do not induce any net change in the copy number and are often associated with uniparental disomy. These phenomena have long been reported to be associated with diseases and particularly in cancer. Losses/gains of genomic regions are often correlated with lower/higher gene expression. On the other hand, loss of heterozygosity (LOH) and cn-LOH are common events in cancer and may be associated with the loss of a functional tumor suppressor gene. Therefore, identifying recurrent CNV and cn-LOH events can be important as they may highlight common biological components and give insights into the development or mechanisms of a disease. However, no currently available tools allow a comprehensive whole-genome visualization of recurrent CNVs and cn-LOH in groups of samples providing absolute quantification of the aberrations leading to the loss of potentially important information.To overcome these limitations, we developed aCNViewer (Absolute CNV Viewer), a visualization tool for absolute CNVs and cn-LOH across a group of samples. aCNViewer proposes three graphical representations: dendrograms, bi-dimensional heatmaps showing chromosomal regions sharing similar abnormality patterns, and quantitative stacked histograms facilitating the identification of recurrent absolute CNVs and cn-LOH. We illustrated aCNViewer using publically available hepatocellular carcinomas (HCCs) Affymetrix SNP Array data (Fig 1A). Regions 1q and 8q present a similar percentage of total gains but significantly different copy number gain categories (p-value of 0.0103 with a Fisher exact test), validated by another cohort of HCCs (p-value of 5.6e-7) (Fig 2B).aCNViewer is implemented in python and R and is available with a GNU GPLv3 license on GitHub https://github.com/FJD-CEPH/aCNViewer and Docker https://hub.docker.com/r/fjdceph/acnviewer/.aCNViewer@cephb.fr.